A variety of energy sources are used in creating hot water for commercial and residential use including electric, solar, and various fuels. Natural gas and propane are preferred by some customers due to, for example, the relatively quick heating rate. These fuels are supplied as a gas that is burned in a combustion chamber to provide heat energy to raise the water temperature.
Temperatures in the combustion chamber are relatively high and can, for example, reach 600 degrees Fahrenheit or higher during normal operation. A flame is created by burning a mixture of the gaseous fuel and air. Proper combustion requires that the air and fuel are provided within a particular ratio to ensure, for example, complete combustion and avoid wasted fuel or the production of unwanted by-products such as carbon monoxide.
In certain conditions, such as if a water heater appliance is installed in a dusty area containing above average levels of, for example, dirt, oil, or lint, the air intake of water heater can become clogged. The lack of sufficient air can cause the temperature of the combustion chamber to become too hot. As another example, a flammable vapor event such as the ignition of vapor from liquid fuel present near the water heater can also create elevated temperatures in the water heater combustion chamber.
Accordingly, it is desirable to monitor temperature and terminate the combustion process by, for example, shutting off the gas flow if the temperature reaches unsafe levels. However, challenges exist with conventional approaches to monitoring temperature at a combustion chamber for a water heater appliance.
One conventional approach is the use of a temperature-dependent switch placed in direct contact with an outer surface of the wall of the combustion chamber. Once the outer surface of the wall sufficiently heats the switch to a predetermined maximum temperature, the switch is activated so as to cause a control system to close off the flow of gas. However, because the switch must be placed in contact with the combustion chamber wall, it does not provide a direct measurement of the temperature of the combustion process. Instead, heat must be transmitted to the wall of the combustion chamber before the switch can be triggered due to an unsafe condition. In some configurations or conditions, the switch may be undesirably influenced by ambient temperatures. For instance, relatively low ambient temperatures may increase the amount of heat drawn from the wall of the combustion heater (e.g., before that heat can be conducted to the switch). The increased heat drawn from the wall may hinder or prevent the switch from detecting an unsuitably high temperature within the combustion chamber. In turn, it may be difficult to ensure proper operation of the switch across a wide range of ambient temperatures and conditions.
Other approaches may require a temperature sensor to be mounted on or within the combustion chamber. A control board connected to the temperature sensor may receive signals from the temperature sensor and halt operation of the water heater appliance or burner based on those same signals. However, such approaches may increase the difficulty of assembling and/or installing the water heater appliance. Moreover, such approaches may be unreliable or susceptible to damage (e.g., at the control board).
Accordingly, a water heater appliance including features to address one or more of the above issues would be desirable. In particular, it would be advantageous to have a gas fueled water heater appliance including an improved system for monitoring the temperature of the combustion chamber of the gas fueled water heater appliance.